Adhesives and method of applying to silicone-treated surfaces



Unite ADIESIVES AND METHOD OF APPLYING TO SHICONE-TREATED SURFACES LewisMarks, Jackson Heights, and Allison M. Stern, Mamaroneck, N. Y.,assignors to Polymer Industries Inc., Astoria, N. Y., a corporation ofDelaware No Drawing. Application January 11, 1954, SerialNo. 403,453

8 Claims. (Cl. 216-62) dated August30, 1955.

This invention relates to adhesives, and more particularly to theprocess of applying labels to containers, cloth, paper, or othersurfaces which have been coated with silicones.

A new class of synthetic materials has appeared in recent years, knownas the silicones or organosiloxanes. They have properties heretoforeunknown in other materials and through adaptations have been utilized ina variety of desirable applications. Silicones have been employed byimpregnating cloth therewith to render it water-repellent.

A further application of silicone has been to coat the inside ofcontainers, bottles and the like, by dipping into or exposing them intothe silicone. Among the advantages of using silicone as a surfacecoating are its resistance to adhesion, its chemical inertness, and itsease of application. While the aforesaid properties are most desirable,problems have arisen in labeling surfaces so treated. Further, in theforming of silicone coated paper bags and cartons, the resistance of thematerial to adhesion creates a problem in securing the flaps and tabsthereof.

Previous attempts to overcome the aforesaid difficulty have eitherproven unsatisfactory or not economically feasible. Solvents and wettingagents and even strong acids and alkalies have been employed withoutsuccess. A partial success was achieved by using alkali 'alcoholates towash the surface prior to any attempt at labeling, but the hazards andcost of this operation have made it undesirable. In addition, tl1e useof any of theforegoing methods would necessitate the redesign ofexisting labeling, boxing and bag machines. .A further undesirablefeature of the prior methods is the reduction in the output of themachines caused .by the addition of another step to the process.

Accordingly, it is an object of this invention to provide an economicalmethod of rendering silicone treated surfaces receptive of adherentmaterials.

An object of this invention is to provide a method of affixing labels tosilicone treated surfaces without pretreatment with solvents, Wettingagents, chemicals or the like.

A further object is to provide a means of adhering labels to a siliconecoated surface, so that a permanent bond is achieved.

A still further object of the present invention is to provide anadhesive composition capable of being used in the standard labeling, boxmaking machinery, and the like.

With these and other objects in view, the invention consists of theimprovements hereinafter described and claimed.

As will be seen from the subjoined description, the invention is basedupon the discovery that acidic fluorides,

States Patent 2,782,949 Patented Feb. 26, 1957 even in very lowconcentrations, possess the property of destroying the resistance of asilicone-treated surface to adhesion.

Hydrogen fluoride, even when moderated and ameliorated by the presenceof large quantities of viscous adhesive materials or thickening agents,have proven highly effective.

Other fluorides, such as ammonium bifluoride (ammonium acid fluoride),amine bifiuorides and sodium blfiuoride, are very effective inovercoming :the chemical inertness of the silicones and their adhesionresistance.

Alkaline fluorides have been found to be less active than thosepreviously mentioned, but by adding acids to compositions containingalkaline fluorides, they may be rendered very efiicient.

Thus, it is within the purview of this invention to employ any suitablematerial or materials which either contain hydrogen fluoride or whichcan form hydrogen fluoride in situ, in compositions for the treatment ofsilicone-coated surfaces.

One of the many applications of the present invention lies in theformulation of adhesives. Adhesive bases suitable for use in connectionwith the compositions may comprise: starch and its derivatives,including ethers, esters, oxidation derivatives, torrefaction products,enzyme conversion products, wet and dry conversion products, dextrines,fluidity starches, and unconverted starches of all kinds, such aspotato, rice, corn, wheat, tapioca, waxy maize, waxy sorghum, sweetpotato, rye and sage; flours such as corn, wheat, rye and barley;proteins such as animal'glue, casein, wheat protein, soy protein, zeinand gelatine and their derivatives; gums, suchas arabic, locust bean,tragacan-th and karaya, and their derivatives; a very wide variety ofsynthetic resins, including polyvinyl acetate, polyvinyl chloride, andtheir copolymers, polyamides, amide-formaldehydes,phenolic-formaldehydes, polystyrenes, polyacrylates andpolymethacrylates, ethoxylines, alkyds, polyesters and polyethylenes;synthetic rubbers and natural rubbers of all kinds, and theirderivatives; cellulose and its derivatives, such as ethers and esters;rosin and its derivatives and related products, such as thegasoline-insoluble fraction of pine-wood resin; sugars and theirderivatives; asphalts and tarry materials; pitches derived from fattyoils; linseed oil, factices, and other oily materials; and otheradhesive bases, able to unite one surface with another.

Compositions prepared in accordance with the present invention may bemade to assume a wide variety of forms. Thus the composition has beensuccessfully applied in the form of aqueous solutions, aqueousdispersions, solvent solutions, hot-melt compositions and catalyst orheatsetting resinous compositions.

Two specific examples of an adhesive composition made under the presentconcept, and which may be employed in a labeling, carton-forming, orpaper bag making process, are as follows:

Example 1 347 parts (by weight) water 650 parts (by weight) solubleyellow tapioca dextrine 3 parts (by weight) phenol 500 parts (by weight)60% aqueous solution of hydrogen fluoride, commercial grade Example 2343 parts (by weight) water 644 parts (by weight) soluble yellow tapiocadextrine 3 parts (by weight) phenol 10 parts (by weight) 60% aqueoussolution of hydrogen fluoride The mixtures in both the foregoingexamples are prepared as follows: The water, dextrine and phenol aremixed and heated to near the boiling point. Stirring and 3 heating arecontinued until the dextrine is well dispersed. The mixture is thencooled to room temperature. The 60% aqueous solution of hydrogenfluoride, in the desired proportions depending upon which batch is beingformulated, is then added to the viscous dextrine mixture.

The finished mixture, outlined in either of the two cited examples, canbe applied to the label by means employed in labeling machines, prior topositioning it upon the silicone treated surface.

Another process, which can be employed in labeling, is to apply theadhesive composition to that area of the silicone surface which is to becovered by the label, then positioning thereon the dry label. A stillfurther method is to apply the finished mixture in a thin film to theback of the label, to form the commonly known gum labels. The label maythen be fed into a labeling machine, wherein it is moistened andpositioned upon the silicone tneated surface.

In the manufacture of cartons the adhesive may be applied to the flapsof the blanks in a thin film. Thereafter, the flaps may be suitablymoistened and the carton formed. Alternately, the flaps may be theadhesive applied thereto in the assembling process, in which case nomoistening would be necessary.

In the making of silicone treated paper bags, the adhesive is applied tothe surface just prior to forming, and by means well known in the art.

A third example of an adhesive, which may be employed in theabove-described manner, is the following:

Example 3 375 parts (by weight) water 250 parts (by weight) animal hideglue (190 gram strength) 75 parts (by weight) thiourea 20 parts (byweight) phosphoric acid (75% aqueous) 80 parts (by weight) of a mixtureof 1 part ammonium bi-fluoride; 2 parts of water, and 1 part of 28% aqueous armnonia Example 4 347 parts (by weight) water 650 parts (by weight)yellow soluble potato dextrine 3 parts (by weight) phenol 50 parts (byweight) sodium fluoride 40 parts (by weight) 75% aqueous phosphoric acidThe water and dextrine are heated, as in Example 1; cooled to roomtemperature and the sodium fluoride then added with agitation. Thephosphoric acid is added last.

Silicone coated aluminum foil may be made to adhere to paper by the useof a composition prepared in the following manner:

Example 5 Add to 100 parts (by weight) of water 50 parts (by weight) of30% ammonia solution 50 parts (by weight) of ammonium bi-fluoride Eightparts of this mixture are added to 100 parts of a solution of polyvinylalcohol, such as Elvanol 72- A-5l, manufactured by E. I, du Pont deNemours.

Another specific example of an adhesive composition which can beutilized in securing labels to silicone coated cloth is the following:

Example 6 920 parts (by weight) of an emulsion of polyvinyl acetate inwater (Ex. Du Po'nts 81-900) parts (by weight) dibutyl phthalate 30parts (by weight) aqueous hydro-fluoric acid These materials may bemixed cold. This specific adhesive composition may be either applied tothe label prior to being pressed upon the cloth, or may be applieddirectly to the cloth and the label thereafter placed upon the surfaceso treated.

It will be seen from the foregoing that several methods have beendescribed whereby labels can be secured to silicone treated surfaces, orby which said surfaces may be secured together. In the methods disclosedherein there are present no dangers to the operators of labeling or bagand carton making machines, as the adhesives are free of strong acids oralkalies. In addition, while only a'few of the many adhesivecompositions have been disclosed, it is obvious that many more types arepossible, which can be employed to meet the variable factors encounteredin the labeling process.

Further, it is apparent that the present labeling machine, carton andbag-making machines, need no modification in design or reduction inspeed of operation, as the adhesive requires no special handling.

We claim:

1. The method of securing labels to silicone treated surfaces comprisingthe steps of mixing an acidic fluoride composition with an adhesivethickening agent compatible with said fluoride composition, applyingsaid mixture to the'back of said label, positioning said label upon thesilicone treated surface, and thereafter allowing the mixture to reactwith the silicone during the drying of said mixture upon the surface.

2. The method of securing labels to silicone treated surfaces comprisingthe steps of mixing an acidic fluoride composition of at least and notmore than 35% by Weight with at least and not more than 99.9% of anadhesive thickening agent compatible with said fluoride composition,applying said mixture to the back of said label, positioning said labelupon the silicone treated surface, and thereafter allowing the mixtureto react with the silicone during the drying of said mixture upon thesurface. 3. The method of securing labels to silicone treated surfacescomprising the steps of mixing an acidic fluoride composition with anadhesive thickening agent compatible with the said fluoride composition,spreading said mixture upon that portion of the silicone treated surfaceto be covered by a label, positioning a label upon the adhesive coveredsurface while said surface is still wet and thereafter allowing themixture to react with the silicone during the drying of said mixtureupon the surface.

4. The method of securing labels to silicone treated surfaces comprisingthe steps of mixing an acidic fluoride composition of at least with notmore than 99.9% of an adhesive thickening agent compatible with the saidfluoride composition, coating the back of a label and allowing saidmixture to dry, moistening the back of said label and positioning saidlabel under pressure upon the silicone treated surfaces and thereafterallowing the mixture to react with the silicone during the drying ofsaid mixture upon the surface.

5. The method of forming and fastening a silicone treated carton blankinto a carton comprising the steps of mixing an acidic fluoridecomposition with an adhesive thickening agent compatible with saidfluoride composition, applying said mixture to the tabs of the saidblank," folding said blank into a carton while said mixture is in a wetstate, and thereafter allowng the mixture to react with the siliconeduring the drying of said mixture upon the surface.

6. The method of forming a silicone treated die-cut blank into a cartoncomprising the steps of mixing an acidic fluoride composition with anadhesive thickening agent compatible with said fluoride composition,covering the tabs with the said mixture, allowing the mixture to drymoistening the tabs, while folding said blank into a carton andthereafter allowing the mixture to re act upon the silicone during thedrying of said mixture upon the surface.

7. The method of forming a silicone treated paper bag comprising thesteps of mixing an acidic fluoride composition with an adhesivethickening agent compatible with said fluoride composition, applyingsaid mixture to the tabs, allowing the acidic fluoride to etch thesilicone surface and thereafter forming the said bag.

8. The method of securing labels to silicone treated surfaces,comprising, the steps of preparing a first mixture of 75 parts ofthiourea with 375 parts of water, adding hide glue thereto and allowingsaid glue to soften, heating said first mixture to 140 F. for two hours,and thereafter cooling it to 120 F., preparing a second mixture of 1part ammonium bi-fluoride, 2 parts of water and 1 part of a 28% aqueousammonia, combining 80 parts of the said second mixture with the saidfirst mixture, applying the composition thus formed to a label bypositioning said label in intimate contact with the silicone treatedsurface and thereafter allowing the mixture to react with the siliconeduring the drying of said mixture upon the surface.

References Cited in the file of this patent UNITED STATES PATENTS254,263 Bitterlin Feb. 28, 1882 1,470,772 Simon Oct. 16, 1923 1,471,466Hogeman Oct. 23, 1923 1,980,179 Bergstein Nov. 13, 1934 1,988,265Collings et al Jan. 15, 1935 2,118,386 Swinehart May 24, 1938 2,137,683Flaherty Nov. 22, 1938 2,159,108 Staudt May 23, 1939 2,278,257 Gallagherh Mar. 31, 1942 2,493,984 McKay Jan. 10, 1950 2,716,612 Marks et al Aug.30, 1955

1. THE METHOD OF SECURING LABELS TO SILICONE TREATED SURFACES COMPRISINGTHE STEPS OF MIXING AN ACIDIC FLUORIDE COMPOSITION WITH AN ADHESIVETHICKENING AGENT COMPATIBLE WITH SAID FLUORIDE COMPOSITION, APPLYINGSAID MIXTURE TO THE BACK OF SAID LABLE, POSITIONING SAID LABEL UPON THESILICONE TREATED SURFACE, AND THEREAFTER ALLOWING THE MIXTURE TO REACTWITH THE SILICONE DURING THE DRYING OF SAID MIXTURE UPON THE SURFACE.